Roof Cover Board Derived From Engineered Recycled Content

ABSTRACT

Disclosed herein is a method of manufacturing an improved cover board product with a panel. In some embodiments, the method includes preparing fragments into an assembly; mixing the fragments and an adhesive into a blended core furnish; applying the adhesive to a top side of a bottom layer fabric in the assembly; forming a core mat of the blended core furnish on top of the adhesive; applying the adhesive to a top side of the core mat; applying a surface layer fabric on the top side of the adhesive; pressing the assembly; and cutting and trimming the assembly to form panels.

CROSS-REFERENCE TO RELATED PATENT APPLICATION

This application claims the benefit under 35 U.S.C. § 120 as adivisional of the following non-provisional application U.S. Ser. No.17/069,567, entitled “Roof Cover Board Derived From Engineered RecycledContent,” filed Oct. 13, 2020, which claims the benefit under 35 U.S.C.§ 119(e) of the following provisional application U.S. Ser. No.62/951,933, entitled “Roof Cover Board Derived From Engineered RecycledContent,” filed Dec. 20, 2019 all of which is incorporated herein byreference in its entirety.

BACKGROUND

The following description is provided to assist the understanding of thereader. None of the information provided or references cited is admittedprior art.

Commercial roofs can be classified as either “low slope” or “steepslope”. Low slope roofs have a pitch that is less than 25%. Most lowslope roofs have a pitch of only 2%, Steep slope roofs have a pitch thatis greater than 25%. Low slope roofs have excellent water and punctureresistance and longevity.

Low slope commercial roofs are comprised of four essential layers. Thebase of the assembly is typically a fluted steel deck. Less frequently,oriented strand board (OSB), plywood, or concrete are used as decking. Arigid insulating foam board, such as polyisocyanurate foam board orexpanded polystyrene, is installed directly over the deck. A protectivecover board is positioned directly over the insulating foam and istypically secured with screws that extend through the insulating foamand into the deck. A water-resistant membrane is then installed over theprotective cover board and is attached to the cover board with eitheradhesives or mechanical fasteners.

Additional layers are sometimes incorporated into low slope roofassemblies. In many cases an air and vapor barrier, such as polyethylenefilm (6 mil thick) is installed between the deck and the insulatingfoam. In some cases, rock ballast or concrete pavers can be placedbetween the insulating foam and the cover board.

Many different membrane types can be used for low slope roofs. One ofthe most common is known as “built-up membrane roof” (BUR), which isgenerally comprised of alternating layers of asphalt and fiberglassfelt. Bitumen is used to attach the BUR to the cover board. Modifiedbitumen (MB), thermoplastic single-ply membranes (polyvinyl chloride,thermoplastic polyolefin, polymers based on ketone ethylene ester) orthermoset single-ply membranes (including polymers based on ethylenepropylene diene monomer) are also used as membranes. Yet anothermembrane type is mesh-reinforced membrane coating (MREC), which is basedon alternating layers of acrylic elastomeric resin and polyesterreinforcing mat. In many cases, these membranes are coated on the backside with an adhesive, but they can also be held in place withmechanical fasteners or ballast. In some cases, solvent-based syntheticrubber adhesives or polyurethane adhesives are applied to the coverboard just prior to membrane installation. Sprayed polyurethane foam(2-component) is also used as a membrane. The polyurethane membranebonds to cover board as it cures, which eliminates the need foradhesives or mechanical fasteners.

Commercial roofs serve an array of difficult functions. They protect theinside of the building from hot and cold external temperatures, as wellas precipitation (rain, snow and hail) and extreme humidity conditions.Roof assemblies also have structural requirements. Specifically, theymust support compressive loads due to foot traffic as well as solarpanels, air conditioning units, and other equipment. Furthermore, theroof must be resistant to flame spread.

Designing a roof assembly to meet all of these requirements is quitechallenging. For instance, low-density foams are commonly used toachieve the thermal barrier requirements of the roof. Unfortunately,these low-density foams are easily damaged by compressive or impactloads. Additionally, some of the most common foams used in roofassemblies lose their ability to provide adequate insulation propertiesif they become wet. Excessive moisture in the insulating foam can alsoenable the growth of bacteria and fungi, which can promote rot and otherproblems. Likewise, impact from hail stones or even heavy foot trafficcan compress the foam and cause a reduction in insulating performance.Therefore, it is imperative that the insulating foam be protected fromexcessive compressive force, impacts, and water. Cover boards play acritical role in protecting the insulating foam in the roof assembly.

There is significant seasonal and regional variation in the frequency ofprecipitation events in North America, but on average they can occurabout once every 2-3 days. To the extent that the insulating foam in theroof assembly can tolerate only a limited amount of water exposure, itis critical that the insulating foam is covered with the water-resistanttop membrane as quickly as possible after foam installation. It is notthe primary function of the cover board to provide water protection tothe insulating foam, but it can be helpful for the cover board to resistwater absorption and conduction for at least several hours during theroof assembly construction process. Any water absorbed by the coverboard during the installation process could be trapped in the assemblyafter the membrane is installed. Thus, cover boards, which are installedbetween the foam and the membrane, must be fast and easy to install andshould exhibit water resistance for several hours.

Fast cover board installation can be thwarted in re-roofingapplications. In this situation a second roof assembly is installeddirectly over the original roof assembly. The original roof assemblywill commonly have a curved contour along the perimeter where the flatportion of the roof intersects with the wall. Flashing is typicallyinstalled at this interface and it results in a curved transition. Theinstallation problem along this curved perimeter is predominantly due tothe lack of flexibility in existing cover boards. Specifically, existingroof cover boards have not been designed to accommodate this aspect.

Another challenge in roof systems involves wind “uplift” forces. Thiscan occur as wind travels across the roof and creates an uplift forcedue to the venturi effect. It can also occur when the ventilation systemcreates positive pressure inside of the building and there are air leakson the bottom side of the roof. In the second case, the roof assembly issubjected to the positive air pressure from inside of the building. Ineither case, the cover boards must have the mechanical strength toresist air pressure and secure the foam insulation. In general, coverboards should have an internal bond strength of at least 10 lb/in² (ASTMD1037) in order to provide adequate resistance to wind uplift forces.

In some cases, the cover board serves to resolve a materialcompatibility problem between the insulating foam layer and themembrane. For example, polystyrene foams should not be placed in directcontact with polyvinyl chloride (PVC) membranes due to plasticizerdiffusion from the PVC into the polystyrene.

Some of the desired functions and attributes of cover boards in aroofing application represent apparent contradictions. For instance,cover boards must provide an upper major surface that is receptive toadhesives used to secure the membrane layer. In this capacity, the topsurface of the cover board must allow for some level of absorption ofboth water-based and solvent based adhesives. However, the ideal coverboard would also provide temporary resistance to the absorption ofrainwater. A second apparent contradiction involves the need for thecover board to act as a substrate suitable for mechanical fasteners thatmight be used to attach membranes. Thus, the cover board must be strongenough to retain fasteners and to resist wind uplift forces. For manymaterial types there is a correlation between strength and stiffness,but for a roof cover board application what is needed is a panel that isboth strong and flexible.

It should also be recognized that temperatures on a roof varysubstantially. For instance, night-time temperatures in the winter canbe as low as −20° F., while temperatures on the same roof on a sunny dayin the summer can be as high as 160° F. Thus, cover panels in the roofassembly must have an acceptable level of thermal dimensional stabilityin order to avoid buckling and detachment from adjacent layers in theroof assembly. This condition is significant because many engineeringpolymers could be utilized in a cover board panel to achieve acombination of strength and flexibility, but these same polymers exhibitpoor thermal dimensional stability.

Cover boards used in low slope commercial roof assemblies includefiberglass mat-faced gypsum, fiber reinforced gypsum, cement panels,perlite, OSB and plywood. Less commonly, high density insulating panels(compressed polyisocyanurate core with coated glass mat facers), cementpanels with reinforcement mesh, asphaltic panels (asphalt core withfiberglass facers), and mineral fiber board (stone wool or mineralfiber) can also be used as cover boards. All of these panels havedeficiencies, including lack of sufficient flexibility, for a roof coverboard application. What is needed is a cover board that provides impactprotection to the insulating foam (from hail, foot traffic and heavyequipment), temporary water resistance, fire resistance, wind-upliftconstraint, thermal dimensional stability, and flexibility forre-roofing applications. The coverboard should also be receptive toadhesives and mechanical fasteners.

SUMMARY

Aspects of one embodiment of the present disclosure relate generally toa new and improved cover board product with a panel having dimensions ofabout 4′ width×8′ length×0.125-0.75″ thick. The panel is comprised ofthree discrete layers. A top surface layer is about 0.005-0.050″ thickand is comprised of either paper or a fiberglass web. A bottom surfacelayer is about 0.005-0.100″ thick and is comprised of either paper, afiberglass web, nylon film, polyester film, polypropene film, ortextiles such as cotton. A core layer is about 0.100-0.700″ thick and iscomprised of discrete paper fragments and polypropylene fragments, whichare connected by use of a thermoplastic bonding resin, includingpolyethylene. The bonding resin is generally attached in a randompattern to less than 100% of the paper fragment and polypropylenefragment surface area. The paper fragments are generally shaped asirregular plates with a diameter of about 0.050-2.000″ and a thicknessof about 0.005-0.050″. The polypropylene fragments can have multipleshape types, some of which are irregular. In general, the largestdimension of the polypropylene fragments is about 2.000″, while thesmallest dimension is about 0.050″. The thickness axis of the paperfragments is generally oriented orthogonally to the plane of the panelarticle. The two different fragment types are uniformly distributed inthe core layer relative to each other. The level of paper fragments inthe core layer is about 30-70% on a mass basis. The level ofpolypropylene fragments in the core layer is about 5-30%. The level ofthermoplastic bonding resin in the core layer is about 10-40%. Thedensity of the core layer is about 40-60 pcf. Thus, the core layerincludes small voids in and around the particles, which improvesflexibility. The core layer is attached to the top and bottom surfacelayers by use of a thermoplastic adhesive, including polyethylene.

The structure of the composite is designed to achieve compression loadsupport, sudden impact resistance, wind uplift resistance, fastenerretention, adhesive compatibility, temporary rain protection, low flamespread, thermal dimensional stability, and an exceptional level ofmechanical flexibility. The design promotes rapid and easy installationof the cover board panel in a commercial low slope roof application. Itis especially advantageous in re-roofing applications due to itsexceptional level of flexibility, which allows it to more easily conformto the curved contour of the perimeter region of the roof. The top majorsurface allows for the absorption of adhesives but will temporarilyresist transfer of rain water into the core layer of the board.

Preferred embodiments will perform better in a low slope roofingassembly than other commercially available cover boards, especially withregard to resistance to hail stone impact and mechanical flexibility.Preferred embodiments will be constructed using materials derivedlargely from municipal solid waste, post industrial waste or otherrecycled content. Each square foot of roof cover board diverts between1.0 and 2.0 pounds of waste from landfills, waterways, or incinerators.The conversion process from waste to coverboard does not contaminate orrender the ingredients of the coverboard harmful allowing for thecoverboard to be easily recycled or remade. The recyclability of wastederived roof cover boards aligns with flat roof industry currentpractices of recycling flat roof membranes.

Coverboard Ease of Recycling at The Competitive Set Recycled Content Endof Service Life Gypsum Roof Up to 98% when the The gypsum industry isnot Coverboard product is produced structured to use recycled using flyash. The gypsum in their remaining ~2% is manufacturing processfiberglass used as facer materials. OSB Roof None The OSB industry isnot Coverboard structured to use recycled wood in their manufacturingprocess Polyiso Foam None The polyiso industry is not Coverboardstructured to use recycled foam in their manufacturing process WasteDerived Up to 98%. The waste derived cover Coverboard The remain ~2% isboard manufacturing process facer materials. allows cover boards to berecycled and remade in perpetuity

Aspects of one embodiment of the present disclosure relate generally toa method of manufacturing an improved cover board product with a panel.In some embodiments, the method includes preparing fragments into anassembly; mixing the fragments and an adhesive into a blended corefurnish; applying the adhesive to a top side of a bottom layer fabric inthe assembly; forming a core mat of the blended core furnish on top ofthe adhesive; applying the adhesive to a top side of the core mat;applying a surface layer fabric on the top side of the adhesive;pressing the assembly; and cutting and trimming the assembly to formpanels.

BRIEF DESCRIPTION OF THE DRAWINGS

Aspects of the present disclosure are best understood from the followingdetailed description when read with the accompanying figures. It isnoted that, in accordance with the standard practice in the industry,various features are not drawn to scale. In fact, the dimensions of thevarious features may be arbitrarily increased or reduced for clarity ofdiscussion.

FIG. 1 is a cross-sectional view of layers in a low slope commercialroof system in accordance with an exemplary embodiment.

FIG. 2 is a cross-sectional view of layers in a three-layer flexibleroof cover board in accordance with an exemplary embodiment.

FIG. 3 is a cross-sectional view of layers in a four-layer flexible roofcover board in accordance with an exemplary embodiment.

FIG. 4 is a cross-sectional view of layers in a four-layer plusaggregate flexible roof cover board in accordance with an exemplaryembodiment.

FIG. 5 is a cross-sectional view of layers in a three-layer plus anoverlay flexible roof cover board in accordance with an exemplaryembodiment.

FIG. 6 is a cross-sectional view of layers in a five-layer flexible roofcover board in accordance with an exemplary embodiment.

DETAILED DESCRIPTION

The following disclosure provides many different embodiments, orexamples, for implementing different features of the provided subjectmatter. Specific examples of components and arrangements are describedbelow to simplify the present disclosure. These are, of course, merelyexamples and are not intended to be limiting. For example, the formationof a first feature over or on a second feature in the description thatfollows may include embodiments in which the first and second featuresare formed in direct contact, and may also include embodiments in whichadditional features may be formed between the first and second features,such that the first and second features may not be in direct contact. Inaddition, the present disclosure may repeat reference numerals and/orletters in the various examples. This repetition is for the purpose ofsimplicity and clarity and does not in itself dictate a relationshipbetween the various embodiments and/or configurations discussed.

In an example three-layered embodiment, the bottom layer of thecomposite can be a kraft paper, a fiberglass fabric, nylon film,polyester film, polypropene film or textiles such as cotton. Paperoptions can be untreated. Alternatively, papers can be coated orimpregnated. Impregnation could be accomplished with phenolic or aminoresins. The level of resin impregnation in the paper could be partial orsaturated. Other sheet goods could be used as the bottom layer of thecomposite as long as they have a thickness of less than about 0.010″ andare comprised of materials that will not melt or decompose attemperatures of less than about 400° F. Paper is a preferred bottomlayer in the composite due to its strength, availability, low cost, andability to withstand platen temperatures of about 400° F.

The top layer in the composite can be a fiberglass web or mat.Alternatively, paper or resin impregnated paper could be used as the toplayer of the composite. If a resin impregnated paper is used, it ispreferable that the resin level in the paper be less than the saturationpoint so that the paper retains some ability to absorb adhesives.Fiberglass webs are a preferred material for the top layer of thecomposite because they are strong, non-combustible, porous, and theyhave the ability to withstand platen processing temperatures of about400° F.

It is beneficial for the fabric used in the top layer of the compositeto have a flame spread rating of Class ‘A’ in the ASTM E84 test for thelow slope roof cover board application. Fabrics comprised of fiberglasswill be inherently more resistant to flame spread relative to otherpotential top layer materials, including paper. Flame spread resistancecan be further improved by treating the top layer with an intumescentformula. Suitable intumescent formulas for this technology includeaqueous, carbonific compositions based on pentaerythritol, ammoniumpolyphosphate and melamine or melamine resins. Fiberglass mats can beimpregnated with intumescent formulas of this type. Upon drying, theformula will remain imbedded within the mat and will exist in a dormantstate until it is heated above a temperature of about 450° F. Thisrelatively high activation temperature allows the treated mat to beprocessed in a hot-press at a temperature of 400° F. without activatingthe previously applied intumescent formula. Thus, carbonific formulascan be incorporated into the top layer fabric prior to production of thecomposite, which is quite beneficial. In a fire event the temperature ofthe intumescent formula will exceed 450° F., which will cause theintumescent formula to expand and char. Both of these actions suppressfire. Other types of intumescent formulas, including those based onexpandable graphite, can be applied to the top layer of the composite.However, intumescent coatings based on expandable graphite need to beapplied to the top surface of the composite subsequent to panelproduction because the expandable graphite is activated at temperaturesless than 400° F., which is the platen temperature used to produce thepresent technology. In many cases expandable graphite coatings are alsomore expensive than carbonific formulas, but expandable graphitecoatings can have superior water-resistance. Other additives, suchaluminum trihydrate, boric acid, halogenated compounds, melamine, andantimony-based compounds, can be incorporated into the top surface layerand/or other layers of the composite in order to improve fireresistance.

Paper fragments in the core layer are generally shaped as irregularplates with a diameter of about 0.050-2.000″ and a thickness of about0.005-0.050″. Paper fragments can be made by milling larger pieces ofpaper until the disintegrated material passes a 1″ mesh screen. Thelarger pieces of paper can be newspaper, advertising, office paper,packaging, or other paper products. The paper can be virgin material, orit can be recycled or sourced from waste streams. Generating paperfragments from waste or recycling streams has the advantage of being lowcost and helps to resolve a world-wide sustainability problem. Paperhaving a thickness of less than about 0.010″ is preferred. Paper havinga thickness of less than 0.002″ is most preferred. Thick paper (>0.010″)based on multiple layers of fiber can be used but is less preferred.Thick paper tends to yield points in the composite with relatively lowinternal bond strength. The level of paper fragments in the core layeris about 30-70% on a mass basis. Preferred levels of paper fragments inthe core layer are about 50-60%. Higher levels of paper fragmentscontribute to improved thermal dimensional stability. It should beemphasized that the cellulosic component in the core layer is “paperfragments”, which are different in composition and their impact on panelproperties than cellulosic fibers, wood flour or other wooden particlesor elements.

Polypropylene fragments can have multiple shape types, some of which areirregular. In general, the largest dimension of the polypropylenefragments is about 2.000″, while the smallest dimension is about 0.050″.There are multiple ways to produce polypropylene fragments. One methodinvolves isolating polypropylene articles from waste streams and thenmilling it until the disintegrated material passes a 1″ mesh screen.Generating polypropylene fragments from waste streams has the advantageof being low cost and helps to resolve a world-wide sustainabilityproblem. The irregular shape of the polypropylene fragments helps toachieve voids in the core layer of the composite. The existence of voidsin the core layer helps to promote greater flexibility in the composite.The level of polypropylene fragments in the core layer is about 5-30%.Preferred levels of polypropylene fragments in the core layer are about15-25%. Higher levels of polypropylene fragments contribute to improvedmechanical properties, including compressive and bending strength. Itshould be emphasized that polypropylene fragments are different thanpolypropylene fibers. Likewise, the use of polypropylene fragments inthe core layer of this composite has property effects that are quitedifferent than the effect of polypropylene in a composite based oncellulosic fibers embedded in an extruded polypropylene continuousphase.

Paper fragments and polypropylene fragments in the core layer aregenerally randomly distributed and are connected together with athermoplastic adhesive with random connection points between thedifferent fragments. Polyethylene is a preferred thermoplastic adhesive,but other thermoplastic resins that have a melt point between about200-285° F. can be used. Examples of other suitable thermoplasticadhesives include polystyrene, copolymers of ethylene and vinyl acetate,copolymers of ethylene and butyl acrylate, copolymers of styrene andbutadiene, methacrylate ester polymers, and some copolymers of ethyleneand propylene. Preferred thermoplastic adhesives have relatively lowmolecular weights, which allow them to melt, flow, and then freeze at arelatively fast rate. Selecting thermoplastic adhesives that have theability to quickly cycle between molten and congealed states allows forfaster press cycles in this technology during the panel manufacturingprocess. Melt flow index values can be used to help identify suitablethermoplastic adhesives for this application. Suitable thermoplasticadhesives will have a melt point between about 200-285° F. and a meltflow index (MFI) value greater than about 10 g per 10 minutes (374° F.,2 mm die orifice, 2060 g weight applied to the plunger). Preferredthermoplastic adhesives will have a MFI greater than about 50 g per 10minutes. Most preferred thermoplastic adhesives will have a MFI greaterthan about 300 g per 10 minutes. Thermoplastic adhesives are generallyfree of water, which helps to reduce drying requirements associated withthe production process. Thermoplastic adhesives are typically stablesolids at room temperature. They have a very long shelf-life, they aresafe to handle, and they are relatively easy to incorporate into thecore layer of the composite through simple addition and mixing with thepaper fragments and polypropylene fragments. The level of thermoplasticadhesive in the core layer is about 10-40%. Preferred levels ofthermoplastic adhesive in the core layer are about 15-30%. Higher levelsof thermoplastic adhesive contribute to improved mechanical properties,including compressive, bending and internal bond strength.

The density of the core layer is about 40-66 pcf. Thus, the core layerincludes small voids in and around the fragments, which improve thelevel of flexibility of the panel.

A disadvantage of thermoplastic adhesives is that they are typicallymade and sold as pellets (diameter of about 0.010-0.200″). These pelletshave a tendency to settle out of the mat subsequent to mat formation.Pellets that settle out of the mat are not able to contribute to bondingbetween the paper fragments and polypropylene fragments. Also, therelatively large pellets that remain in the mat melt slowly and themolten pellet contacts a limited number of paper fragments andpolypropylene fragments, which minimizes the binder activity of thethermoplastic adhesive. Exemplary embodiments described herein resolvethese problems by extruding the thermoplastic adhesive into a moltenfilament (diameter of about (0.0001-0.001″) that is combined with thepaper fragments and polypropylene fragments in a mixing process. Themolten filament breaks into fibers as it contacts the tumbling mixtureof paper fragments and polypropylene fragments. In this manner, theamount of fragment surface area that is in contact with thethermoplastic adhesive is substantially increased. Furthermore, theresulting thermoplastic fibers are partially adhered to fragments andthey are in a shape that prevents them from settling out of the mat.

Thermoplastic adhesives can also be applied to the paper fragments andpolypropylene fragments in the form of aqueous lattices or latexemulsions. In this approach the latex is sprayed onto the fragments in amixer. Latex spray droplets cover a very high percentage of the surfacearea of the fragments at a relatively small application level. Thus,this represents a much more efficient way of distributing thermoplasticadhesive onto the surface of the fragments. This approach does result inincreased water content of the fragment mat, which could be problematicin hot-pressing, especially if the mat has a moisture content greaterthan about 4-5%. Since many latex polymer emulsions have a solidscontent of about 40-50%, the maximum amount of latex that can be addedto the paper fragments and polypropylene fragments is about 8-10%. Insome cases, latex addition levels of only 2-10% could be highlybeneficial.

Thermosetting adhesives could be used in place of the thermoplasticadhesive or as a supplement to the thermoplastic adhesive. Suitablethermosetting resins include isocyanates, polyurethanes, phenolicresins, amino resins, epoxy resins, crosslinked polysaccharides, andresins based on soy and poly (amide epichlorohydrin) (PAE).Thermosetting resins can potentially allow for faster production ratesof the composite, as opposed to thermoplastic adhesives. The fasterprocessing rates are due to the ability of the thermosetting resin to berapidly converted from a liquid to a solid at elevated temperature.Thermosetting adhesives can generally cure at a rate that is faster thanthermosetting resins can melt, flow and then congeal. Idealthermosetting resins will exhibit strong adhesion towards both paperfragments and polypropylene fragments. Many thermosetting resins do nothave this ability, but for this application a polyurethane resin basedon polymethylene diphenyl diisocycanate (pMDI) and castor oil has thepotential to bond strongly to both paper fragment and polypropylenefragments. Thermosetting adhesive levels in the core layer of thecomposite could range from about 0-15%.

When paper fragments and/or polypropylene fragments are generated fromrecycled streams or waste streams, they often have some odor. This odortends to diminish during the hot-pressing process. In some cases, thefinished composite panel can have some residual odor that could beobjectionable. We have discovered that certain additives can beincorporated into the core layer in order to substantially reduce theodor. Effective odor blockers include activated carbon, zeolites, sodiumcarbonate and mixtures thereof. Suitable odor blocker levels are about0.05-2.0% by weight of the core layer. Odor blockers can be introducedby dry mixing of the odor blocker, adhesive, paper fragments, andpolypropylene fragments. Very fine odor blocker particles tend todistribute uniformly with the other core raw materials.

The core layer is attached to the top and bottom surface layers by useof thermoplastic adhesive. It is convenient to use thermoplasticadhesives in the form of films, but webs could also be used.Specifically, thermoplastic films or webs can be placed between the coreand a surface layer. Subsequent application of heat and pressureconverts the thermoplastic film or web into a sticky liquid, whicheffectively binds the two different layers together, especiallysubsequent to cooling and solidification of the thermoplastic adhesive.Alternatively, thermoplastic adhesive could be applied onto a majorsurface of one of the layers prior to the assembly and pressing processto achieve the same adhesion effect. Thermoplastic adhesives suitablefor this function will have a melt point of about 190-320° F. When afiberglass mat is used as the top layer, it will be helpful to use athermoplastic adhesive between the top layer and the core that has ahigh molten viscosity at a temperature of about 320-400° F. so that themolten adhesive does not over-penetrate the fiberglass mat and foul thetop press platen. In yet another approach, thermosetting adhesives couldbe used to join the three different layers. The adhesive applicationlevel between the layers of the composite can range from about0.005-0.02 lb/ft².

The process for making the composite cover board involves multiplesteps. Different embodiments may include different variations orarrangements of the steps, including additional or fewer steps. In afirst step fragments of paper and polypropylene are generated by feedingrelatively large sheets of paper and relatively large articles ofpolypropylene into a mill, which mechanically disintegrates the paperand polypropylene into fragments. The mill is equipped with a screenthat has a mesh size of about 1″. Thus, paper fragments andpolypropylene fragments that are being processed inside of the mill willcontinue to be reduced in size until they are able to pass through thescreen. In this manner, fragments will be generated that have a size ofabout 1″ or less. If desired, a smaller or larger mesh size could beused to yield smaller or larger fragments. Optionally, thermoplasticadhesive could be processed through the mill as well. Different millscould be used for each of the fragment types or they could be processedtogether through the same mill. When a single mill is used, there willbe a tendency for the three components to be mixed together. Additionalmixing can be achieved by processing the components through a secondaryblender. The secondary blender allows for the convenient application ofadditional adhesives and/or other functional additives. The secondaryblender will be especially beneficial for the introduction of liquidadditives or additives that need to be uniformly distributed within thecore furnish. Optionally, the paper fragments only or the mixture ofpaper fragments and polypropylene fragments can be processed through adryer prior to the secondary blender. The blended core furnish will thenbe conveyed to a forming station.

At the beginning of the forming station a bottom layer fabric (48″ wideor greater) will be unwound onto a horizontal belt, which will conveythe bottom layer fabric in a forward direction. An adhesive will then beapplied to the top side of the bottom layer fabric. As previouslystated, the adhesive could exist as a film or it could be a liquid,which could be applied as a spray, or a curtain, or it could be floodcoated. Alternatively, the adhesive could be a thermoplastic that isapplied to the bottom layer fabric in an extrusion process. The blendedcore furnish is then deposited on top of the previously appliedadhesive. The basis weight of the core furnish will be about 1.5-2.5lb/ft². Rakes or other devices can be used to ensure that the depositedcore furnish is uniformly distributed at the targeted basis weight. Moreadhesive will then be applied to the top side of the core mat. Finally,the top layer fabric (48″ wide or greater) will be unrolled andpositioned over the adhesive that was previously applied to the corelayer mat. In some cases, the resulting layered assembly will beprocessed through opposing rolls in order to compact it.

The resulting assembly will then be conveyed into a hot-press. Thesurface temperature of the top and bottom platens will be about 350-425°F. Pressure of about 20-800 lb/in² will be exerted on the assembly byuse of the hot-press for a period of about 2-10 minutes. The appliedpressure could be constant. Under this condition the thickness of themat will actually decrease during the pressing event. Alternatively, thethickness of the mat can be held constant. Under this condition thepressure on the mat will initially be relatively high, such as 600-800psi, and will decrease to about 50 psi, or even lower, as the pressingevent continues. In general, the gap between the top and bottom platensduring pressing will be about 0.25-1.00″. A preferred gap between theplatens is about 0.50″ when the basis weight of the core furnish in theassembly is about 1.9-2.2 lb/ft². If the moisture content of theassembly is greater than about 4-5%, then venting cycles might be neededduring the hot-pressing process. The hot, compacted assembly will thenbe processed through a cold press in order to freeze or congealthermoplastic components in the composite. The cold press should havetop and bottom platen surface temperature values of about 30-80° F. Thepressure in the cold press will be maintained at about 5-25 psi. The gapbetween the platens should be equal to the targeted thickness of theresulting panel. The cold press time should be about 2-10 minutes andmust be sufficient to cool the composite throughout its thickness to atemperature of less than about 190° F. Most ideally, the compositeshould be cooled to a temperature of less than about 110° F. prior toexiting the cold press.

Subsequent to cold pressing, the consolidated composite can be cut intopanels, such as panels having a dimension of 4′ wide×8′ long, which areuseful for a roof cover board application. Panels can be stacked,treated with edge sealant, banded and packaged.

A summary of example steps in the described composite manufacturingprocess includes:

-   -   1. Prepare fragments of paper and polypropylene.    -   2. Optionally, dry the paper fragments.    -   3. Mix the paper fragments, polypropylene fragments and adhesive        into a blended core furnish. Optionally, additional additives        can be incorporated into the core furnish at this step.    -   4. Apply adhesive to the top side of the bottom layer fabric.    -   5. Form a mat of the core furnish on top of the adhesive that        was previously applied to the bottom layer fabric.    -   6. Apply adhesive to the top side of the core mat.    -   7. Apply a surface layer fabric on the top side of the adhesive        that was previously applied to the top side of the core mat.    -   8. Hot-press the assembly.    -   9. Optionally, use venting cycles during the hot-pressing        process.    -   10. Cold-press the assembly.    -   11. Cut and trim the consolidated assembly to form panels.    -   12. Stack the panels on pallets or bunks.    -   13. Optionally, apply sealant to the edge of the panels.    -   14. Band and optionally package the stacked panels.

In an example four-layered embodiment, additional layers can beincorporated into the composite to achieve improved resistance to hailstones and rain water. Specifically, a four-layered composite can beprepared. A bottom outer layer in this composite is paper, a fiberglassweb, nylon film, polyester film, polypropene film, or textiles such ascotton (0.005-0.100″ thick). Moving upward, a second layer is comprisedof paper fragments and polypropylene fragments that are connectedtogether with thermoplastic or thermosetting binder. Moving upward, athird layer is comprised of fiberglass web (0.005-0.010″ thick) that hasbeen treated with a carbonific intumescent for flame spread resistance.Moving upward, a fourth layer is comprised of consolidated polypropylenefragments. The fourth layer is created by depositing polypropylenefragments or other polypropylene particles onto the top side of thefiberglass mat prior to pressing. Alternatively, the top layer fragmentsor particles could be a different polymer with a melt point greater thanabout 300° F. The fragments are consolidated during the pressingprocess. See FIG. 3. As a further option, small aggregate could be addedto the assembly on top of the upper fourth layer. Aggregate couldinclude stone, glass, dust or wood chips. Said aggregate would bepressed into the polypropylene in the upper fourth layer, which couldimprove fire resistance and/or aesthetics. The lower three layers areconnected together with polyethylene film (about 0.001-0.003″ thick) ora suitable alternative thermoplastic or thermosetting adhesive. See FIG.4.

Additional four layered embodiments can be achieved by incorporation ofa fourth upper layer comprised of plastic sheets, additional fiberglassmat, resin impregnated paper (medium density or high density), melaminecoatings, metals, fabrics or other sheet goods. The additional overlaycould be incorporated into the composite during the primary productionprocess or subsequent to the primary production process. The fourthupper layer can improve structural properties, water hold-out,air-barrier properties, and aesthetics. See FIG. 5.

In an example five-layered embodiment, additional layers can beincorporated into the composite to achieve improved resistance to hailstones and rainwater, but maintaining the ability to absorb adhesives.Specifically, a five-layered composite can be prepared. A bottom outerlayer in this composite is paper, a fiberglass web, nylon film,polyester film, polypropene film, or textiles such as cotton(0.005-0.100″ thick). Moving upward, a second layer is comprised ofpaper fragments and polypropylene fragments that are connected togetherwith thermoplastic or thermosetting binder. Moving upward, a third layeris comprised of a film (0.0005-0.003″) composed of polyether etherketone polymer (PEEK), which has very high tensile strength, excellentpuncture resistance and has almost no capacity to absorb water. Movingupward, a fourth layer is comprised of paper (0.005-0.100″ thick).Moving upward, a fifth and top layer is comprised of glass fiber web(0.005-0.010″ thick) that has been treated with a carbonific intumescentfor flame spread resistance. The five layers are connected together withpolyethylene film (about 0.001-0.003″ thick) or a suitable alternativethermoplastic or thermosetting adhesive. The bonding resin connectingthe fourth and fifth layers can be discontinuous in order to promotesome level of absorption or fluid transfer through the fiberglass weband into the paper (fourth layer). The third layer (PEEK film) iscontinuous and is highly resistant to the absorption of water, solventsor oils. Interactions between the PEEK layer and the underlying corelayer allow this composite to have exceptional levels of impactresistance, especially to hail stones. The upper surface of thecomposite also has the ability to absorb adhesives, but the compositewill prevent water from passing vertically through to the underlyinginsulating foam. These valued properties are achieved while maintaininga high level of mechanical flexibility. This embodiment is illustratedin FIG. 6. PEEK films suitable for this invention are commerciallyavailable from Victrex USA Incorporated [West Conshohocken, Pa.] underthe trade name APTIV 1000. Alternatively, similar embodiments couldinvolve replacement of PEEK film with thin films that are wholly orpartially comprised of different high performance thermoplasticpolymers, including polyetherimides, polyether sulfones, orpolyphenylene sulfides, which also have exceptional tensile strength,puncture resistance, hydrophobicity and melt points greater than 400° F.Likewise, the third layer in this composite could be partially or whollycomprised of high-performance thermosetting polymers, such aspolydicyclopentadiene or a polyimide. In yet another embodiment, thethird layer can be a resin impregnated paper.

By way of an example (Example 1), panels in accordance with thedescribed embodiment were made in the following manner. A recycled wastestream was mined for paper, polyethylene and polypropylene materials.The isolated materials were milled to pass screens having a mesh size of1″ in order to yield a mixture of paper fragments (0.1-2.0″ in diameter,0.0005-0.010″ thick), polyethylene fragments (0.1-2.0″ in diameter,0.0005-0.010″ thick), and polypropylene fragments (0.1-2.0″ in diameter,0.0005-0.010″ thick). The component ratio was about 60:20:20 by weight,respectively, on a dry basis. The moisture content of the paperfragments was about 25%. The fragments were uniformly mixed and thendeposited onto a layer of low-density polyethylene film (48″ wide, 3 milthick) from Petoskey Plastics [Detroit, Mich.]. The polyethylene filmwas positioned over a layer of kraft paper, known as KL42, (54″ wide, 42lb per ream) manufactured by WestRock (Solvay, N.Y.). Both the kraftpaper and polyethylene film were transported on a horizontal conveyerwhile the fragments were being deposited. Fragments deposited on top ofthe polyethylene film were randomly oriented. The height of thedeposited fragments was controlled with spinning rakes that werepositioned about 3″ above the polyethylene film in order to achieve abasis weight of the deposited fragments of about 2.2 lb/ft² (dry basis).A second layer of low-density polyethylene film (48″ wide, 3 mils thick)was unwound over the top of the deposited fragments and a layer offiberglass web with intumescent fire retardant (48″ wide), known as WTFR 10SR—48¼ White, from Atlas Web Technologies [Atlanta, Ga.] was placedon top of the second layer of polyethylene film. Strips of kraft paper(3″ wide, 42 lb/ream) were applied to the left and right edges of thetop side of the mat adjacent to the fiberglass layer. The assembly wasloaded into a first hot-press (54″ width×8′ length) with a bottom platen(T=385° F.) and a top platen (T=365° F.). The hot-press closed on theassembly and pressure (about 80 psi) was applied to the mat such thatthe gap between the top and bottom platens was maintained at about0.50″. After a period of 30 s the press opened for a period of 10 s inorder to release steam that had developed in the core of the assembly.The press then cycled in a similar manner between closed and openpositions seven more times, such that the total press time in the closedposition was 4 minutes. The assembly was then transported to a secondhot-press (of similar dimensions) and the same pressing cycle wasrepeated. The assembly was then transported to a third press (of similardimensions). The platens on the third press were maintained at atemperature of only 60° F. The assembly was pressed in the cold press ata pressure of about 10 psi for a period of about 5 minutes and 20seconds. The cold press remained closed during this entire pressingperiod (no venting cycles). The cold press was then opened, and thecompressed assembly was transported to a set of saws that trimmed theedges of the assembly to a width of 48″. The assembly was further cutinto segments that were 8′ in length. In this manner, panels(4′×8′×0.50″) were generated. The edges of the panels were treated witha water-based edge sealant, known as CBS 156 RM Blue HP, and comprisedof a mixture of water, colorant, wax and acrylic latex, from theWillamette Valley Company [Eugene, Oreg.].

The resulting panel was useful as a cover board for roof assemblies. Inthis application the panel had exceptional flexibility that wasparticularly advantageous in re-roofing cover board applications. Thepanel was cut into test specimens (2″×2″ and 3″×6″), which weresubjected to internal bond and flexure tests (per ASTM D1037, 4.72″ spanfor flexure, 0.05 inch/minute strain rate for both TB and flexure test).Density values of the specimens were also measured.

TABLE 1 Average Properties of Panel from Example 1. PROPERTY AVERAGEVALUE Internal Bond Strength 25 lb/in² Modulus of Rupture (Flexure)1,600 lb/in² Modulus of Elasticity (Flexure) 35,000 lb/in² Density 55lb/ft³ Caliper 0.50 inches

The panel (upon being installed in an assembly comprised of plywood,polyisocyanurate foam, and cover board) was also able to resist an iceball (2″ diameter) impact at 105-110 feet/second without rupture of thetop fiber glass fabric on the cover board. The top major surface of thepanel supported a column of water without significant levels ofabsorption into the core layer for a period of 24 hours. Additionally,the panel achieved a Class ‘A’ rating for flame spread in the ASTM E84test. Furthermore, it was receptive to common membrane adhesives andfasteners. This panel was particularly unique in that it had very highlevels of flexibility.

As previously mentioned, cover boards used for low slope commercialroofs include gypsum with fiberglass surface layers, fiber reinforcedgypsum, cement panels with paper surface layers, OSB and plywood.Unfortunately, these products are not sufficiently flexible at a levelthat is suitable for re-roofing applications (especially on the curvededge of the roof). Flexibility in panels can be generally expressed as aminimum bending radius, which is the minimum radius of a circle thatcould be made by bending, but not breaking the panel. The bending radiusof a panel can be estimated through calculations and flexural MOE andMOR test values.

TABLE 2 Minimum Bending Radius Values for Roofing Cover Boards and OtherMaterials Minimum Density Thickness Bending Panel Type (lb/ft³) (inches)Radius (ft) USG Fiber Reinforced Gypsum 66 0.50 30 GP DensDeck DuragaurdRoof Board 48 0.50 12 GP DensDeck Roof Board 48 0.50 8 Plywood 34 0.506.5 USG Securock (Gypsum with Glass 41 0.50 6 Mat Surface) USG CementRoof Board 58 0.50 6 GP DensDeck Prime Roof Board 48 0.50 6 OSB 40 0.505.3 Wood/Plastic Composite (60% 65 0.50 2.2 Polypropylene, 40% WoodFiber) Wood/Plastic Composite (57% 65 0.50 1.9 Polypropylene, 40% WoodFlour, 3% Compatiblizer) Panel from Example 1 55 0.50 0.69 Note: Minimumbending radius values for the USG and GP panels were reported in productliterature from each company. All other minimum bending radius valuesshown were calculated based on flexural MOE and MOR values.

The following calculations were used to determine minimum bending radiusvalues:

Flexural MOR=3FL/2bd ² (center-point bending)

Flexural MOE=L ³ m/4bd ³ (center-point bending)

Circle Arc Equation: L=2r cos⁻¹(1−(h/r))

Where,

F=force applied to the center of a beamL=beam span or length of arcb=beam widthd=beam depthm=slope of beam deflection curve (F/h)r=radius

The data shown in Table 2 provide a clear demonstration that theproperties of the panel described in Example #1 of this application areunique for a roofing panel and beneficial in terms of flexibility. Infact, the flexibility of the panel described in Example #1 is greaterthan that of traditional wood plastic composites, even those with only40% wood content.

Previous panels have been created using composites that utilize rawmaterials based on waste streams. For example, U.S. Pat. No. 8,394,505describes a building and construction element that contains a basiclayer of pressed pulp of laminated food packages (column 1, lines42-43). The laminated food packages are described as being made of paperwith walls on at least one side that are covered by a waterproof sheet(column 1, lines 19-21). The waterproof sheet is usually made of plasticor aluminum (column 1, line 22). An example of this type of packagingmaterial is Tetra-Pak (column 1, line 24). In a preferred embodiment thebasic layer is comprised of particles that have a dimension that is lessthan 30 mm (column 1, line 47). This basic layer is covered on at leastone side with a plastic sheet and has outside cover layers (column 1,lines 43-44). The construction element is made by grinding Tetra-Pakpackages into particles smaller than 30 mm and then washing and dryingthem. The ground particles are spread evenly on a sheet of paper. Thetop side of the Tetra-Pak particles is then covered with a plasticsheet, which is then covered with a cover layer. The top cover layer canbe paper (column 2, line 25). The assembly is then pressed at 160-190°C. and is then cold-pressed (column 2, lines 12-21). The resulting boardcan have dimensions of 10 mm×2800 mm×1200 mm with a density of 800 kg/m³and a bending strength of 5.5 MPa (column 2, lines 21-27). In Englishunits the board would have dimensions of 0.394″×9.19′×3.94′, a densityof 49.9 lb/ft³, and a bending strength of 798 lb/in². The board isreportedly suitable for flooring applications as well as a ceramic tilesubstrate (column 2, lines 33-36). It can be laminated to insulatingmaterials, such as foams, to make sandwich type panels (column 2, lines37-47). The patent further describes the basic element laminated on onemajor surface to foam and laminated on the opposing major surface toaluminum or a plastic sheet (column 2, lines 55-57).

There are some key differences between the composition described in U.S.Pat. No. 8,394,505 and the composition of the exemplary embodiments ofthe present disclosure. The basic particle used in the core of thecomposite described in U.S. Pat. No. 8,394,505 is a laminate comprisedof paper and either aluminum or plastic, while the basic particlesdescribed in the exemplary embodiments are paper fragments (notlaminated) and polypropylene fragments (not laminated). Likewise, thetechnology described in U.S. Pat. No. 8,394,505 does not use a secondaryadhesive in the core layer. Presumably, plastic that is laminated to thepaper acts as an adhesive described by U.S. Pat. No. 8,394,505. To theextent that this is true, the effective adhesive distribution isdifferent in U.S. Pat. No. 8,394,505 than it is in the exemplaryembodiments. Specifically, the adhesive in the core layer of theexemplary embodiments will be more randomly distributed relative to thepaper fragments, while many of the paper particles in the core layer ofthe technology described by U.S. Pat. No. 8,394,505 will have plasticadhesive over 100% of the surface area on at least one of their majorsurfaces. Additionally, the technology described by U.S. Pat. No.8,394,505 will contain significant levels of aluminum in the core layer,while the exemplary embodiments have a core layer that is essentiallyfree of aluminum or other metals. Furthermore, the exemplary embodimentsutilize discrete polypropylene fragments in the core layer, whereas thetechnology described by U.S. Pat. No. 8,394,505 does not utilize anypolypropylene fragments. These compositional differences in the corelayer are meaningful and they result in significant propertydifferences. For instance, the bending strength of the board made inaccordance with U.S. Pat. No. 8,394,505 is about half of that associatedwith the board made using the exemplary embodiments (798 lb/in² vs 1600lb/in²).

U.S. Patent Publication 2019/0119918 is directed towards a roof coverboard that includes a core that is comprised of recycled materials(0005). The core of the composite can be made by shredding recycledmaterials and then heating and compressing them to form a core (0016).Reportedly, no additional binders are used (0016). Facing layers areattached to the major surfaces of the core and include paper andfiberglass (0018). Facers can be attached to the core by use of theplastic within the core. Thus, secondary adhesive between the core andthe facing layers is not required (0020). A key feature of the corelayer is the existence of horizontal regions of the board that containelevated levels of plastic (0023, 0024). These regions are targetedtowards zones of the panel that will receive mechanical fasteners. Thehigh plastic regions reportedly improve fastener retention and provideenhanced sealing (0023). The publication is somewhat vague with regardto a compositional description of the composite. Likewise, thepublication provides no examples or measured properties. A keycharacteristic of the core of the composite is the existence ofhorizontal zones that are targeted for receiving fasteners and containelevated levels of plastic. This design is different than that of theexemplary embodiments. Use of supplemental adhesives and other additivesin the exemplary embodiments would appear to be outside of concepts thatwere contemplated by the publication.

Prior panel technologies fail to address specific design features of thepanel related to adhesive compatibility, rain resistance, protectionfrom external compressive forces, hail resistance, fire resistance,thermal dimensional stability, or flexibility.

The foregoing outlines features of several embodiments so that thoseskilled in the art may better understand the aspects of the presentdisclosure. Those skilled in the art should appreciate that they mayreadily use the present disclosure as a basis for designing or modifyingother processes and structures for carrying out the same purposes and/orachieving the same advantages of the embodiments introduced herein.Those skilled in the art should also realize that such equivalentconstructions do not depart from the spirit and scope of the presentdisclosure, and that they may make various changes, substitutions, andalterations herein without departing from the spirit and scope of thepresent disclosure.

What is claimed is:
 1. A method of manufacturing an improved cover boardproduct with a panel, the method comprising: preparing fragments into anassembly; mixing the fragments and an adhesive into a blended corefurnish; applying the adhesive to a top side of a bottom layer fabric inthe assembly; forming a core mat of the blended core furnish on top ofthe adhesive; applying the adhesive to a top side of the core mat;applying a surface layer fabric on the top side of the adhesive;pressing the assembly; and cutting and trimming the assembly to formpanels.
 2. The method of claim 1, wherein the fragments include paperand polypropylene.
 3. The method of claim 1, wherein the core mat iscomprised of discrete paper fragments and polypropylene fragments, whichare connected by use of a thermoplastic bonding resin.
 4. The method ofclaim 3, further comprising drying the paper fragments.
 5. The method ofclaim 3, wherein the paper fragments are shaped as irregular plates. 6.The method of claim 1, wherein the panels comprise a top surface layercomprised of a fiberglass web, a bottom surface layer comprised ofpaper, and a core layer disposed between the top surface layer and thebottom surface layer.
 7. The method of claim 6, wherein the core layerincludes paper fragments and polypropylene fragments comprisingmunicipal waste, post-industrial waste, and other recycled content. 8.The method of claim 6, wherein the core layer comprises recycledmaterials.
 9. The method of claim 6, wherein paper fragments andpolypropylene fragments are uniformly distributed in the core layerrelative to each other.
 10. The method of claim 6, wherein the corelayer includes odor blockers.
 11. The method of claim 6, wherein thecore layer includes small voids in and around the particles.
 12. Themethod of claim 6, wherein different fragment types are randomlydistributed in the core layer relative to each other.
 13. The method ofclaim 6, wherein the adhesive is attached in a random pattern of asurface area of recycled fragments in the core layer.
 14. The method ofclaim 1, wherein the adhesive is a thermoplastic adhesive.
 15. Themethod of claim 1, wherein pressing includes hot-pressing and coldpressing.
 16. The method of claim 15, wherein hot-pressing includesusing venting cycles.
 17. A method of manufacturing an improved coverboard product with a panel, the method comprising: mixing the fragmentsand an adhesive into a blended core furnish; applying the adhesive to atop side of a bottom layer fabric in an assembly; forming a core mat ofthe blended core furnish on top of the adhesive; applying the adhesiveto a top side of the core mat; applying a surface layer fabric on thetop side of the adhesive; pressing the assembly of the bottom layerfabric, the core mat, the surface layer fabric, and the adhesive; andcutting and trimming the assembly to form panels.
 18. The method ofclaim 17, wherein the bottom layer fabric is comprised of paper.
 19. Themethod of claim 17, wherein the core mat is comprised of discrete paperfragments and polypropylene fragments, which are connected by use of athermoplastic bonding resin.
 20. The method of claim 17, wherein thesurface layer fabric is comprised of a fiberglass web.